Decoding Pear Tree Bacteria Genes and Phage Disease Defense

Jenn Hoskins
8th March, 2024

Decoding Pear Tree Bacteria Genes and Phage Disease Defense

Image Source: Natural Science News, 2024

Key Findings

  • Study in Berkeley found unique bacterial strains in ornamental pear trees that can infect crops
  • A new virus that kills these bacteria was discovered and may protect crops without antibiotics
  • The virus effectively reduced disease in pear fruit, showing promise as a biocontrol agent
Bacterial infections in plants are a significant threat to global agriculture, often leading to severe crop losses. One such bacterial menace is the Pseudomonas syringae species complex, which encompasses a variety of strains that target a wide range of plant species. A recent study by researchers at the University of California, Berkeley[1] has shed new light on this complex, focusing on isolates from diseased Callery pear trees and exploring the potential of bacteriophages—viruses that infect bacteria—as a method to control these plant pathogens. The study involved the genomic characterization of two P. syringae isolates from Callery pears in Berkeley, California, collected in 2019 and 2022. The isolates were found to belong to a group known as phylogroup 2, which includes strains from similar hosts. The researchers discovered each isolate had a unique set of effector proteins. These proteins are critical as they can either promote disease or trigger immune responses in plants[2]. The conservation of effectoromes—the collection of effector genes—across the isolates highlights the evolutionary strategies these bacteria employ to infect their hosts. In addition to understanding the bacterial isolates, the researchers isolated a lytic bacteriophage, a type of virus that destroys its bacterial host. This phage was genomically similar to other phages known to infect the Pseudomonas syringae pv. actinidiae, responsible for kiwifruit canker[3]. Considering the challenges of bacterial resistance arising from traditional control methods like copper and antibiotics, phages represent a promising alternative for biocontrol. The phage's potential as a biocontrol agent was tested in planta, meaning within the plant itself. The results were promising as the phage effectively mitigated symptoms in immature pear fruit, regardless of the Pss strain. This finding is significant, considering the diverse lifestyles and virulence strategies of the P. syringae complex[4]. The ability of phages to evolve and potentially drive changes in host populations by moving genes among bacterial genomes is a key aspect of their utility in biocontrol[4]. The study also highlights the risk of spillover of pathogens from ornamental to commercial plants, which could have serious implications for local fruit production. However, it simultaneously offers a solution in the form of phages. The novel phage discovered by the UC Berkeley team is a testament to the potential of phages as sustainable antimicrobials in agriculture. This aligns with previous research that has demonstrated the efficacy of phages in controlling bacterial pathogens in crops such as citrus and kiwifruit[3][5]. The resistance of bacteria to phages is a natural occurrence, and understanding this interaction is crucial for the effective use of phages in biocontrol. For instance, resistance to the ΦPsa374-like phages in kiwifruit was overcome by mutations in the phage's tail fibre and a structural protein[3]. Such insights into phage-bacteria interactions are essential for developing robust phage-based treatments. In summary, the study from UC Berkeley not only enhances our understanding of the P. syringae species complex but also opens the door to innovative, eco-friendly methods of disease control. By harnessing the power of bacteriophages, scientists can offer agriculture a tool to combat pathogens without contributing to the problem of antibiotic resistance. The continued exploration of phage-host dynamics and the environmental resilience of phages[5] will be crucial in developing effective biocontrol strategies to safeguard our crops.

BiotechGeneticsPlant Science


Main Study

1) Genomic characterization of Pseudomonas syringae pv. syringae from Callery pear and the efficiency of associated phages in disease protection.

Published 5th March, 2024

Related Studies

2) Effector Identification in Plant Pathogens.

3) A lipopolysaccharide-dependent phage infects a pseudomonad phytopathogen and can evolve to evade phage resistance.

4) Drivers and consequences of bacteriophage host range.

5) Biological and Molecular Characterization of the Lytic Bacteriophage SoKa against Pseudomonas syringae pv. syringae, Causal Agent of Citrus Blast and Black Pit in Tunisia.

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